Role of code validation and certification in the design environment

The question frequently asked after a computational fluid dynamics (CFD) solution has been obtained, How do I know my answer is correct?, is considered. Most engineering organizations using CFD codes in support of their design processes attempt to assess this issue and to reduce the risks incurred by evaluating the usability of the results. Whereas there are several forms of risk, the primary issues focused on in this work are accuracy and reduced variability (robustness). The role of benchmark or validation studies in establishing a code's accuracy is examined. Examples are presented illustrating the difficulty in relying on benchmark studies to validate a code for design usage. mays of reducing code usage variability are also suggested, including performing numerical experiments and design calibrations.